我在玩苹果的新Swift编程语言，遇到了一些问题…
目前我试图读取一个plist文件，在Objective-C中，我会做以下工作来获取内容作为NSDictionary:
NSString *filePath = [[NSBundle mainBundle] pathForResource:@"Config" ofType:@"plist"];
NSDictionary *dict = [[NSDictionary alloc] initWithContentsOfFile:filePath];
我如何得到一个plist作为一个字典在Swift?
我假设我可以得到路径到plist:
let path = NSBundle.mainBundle().pathForResource("Config", ofType: "plist")
当这工作(如果它是正确的?):我如何获得内容作为一个字典?
还有一个更普遍的问题:
是否可以使用默认的NS*类?我想是的……还是我遗漏了什么?据我所知，默认框架NS*类仍然有效，可以使用吗?
当前回答
这个答案使用Swift本机对象而不是NSDictionary。
斯威夫特3.0
//get the path of the plist file
guard let plistPath = Bundle.main.path(forResource: "level1", ofType: "plist") else { return }
//load the plist as data in memory
guard let plistData = FileManager.default.contents(atPath: plistPath) else { return }
//use the format of a property list (xml)
var format = PropertyListSerialization.PropertyListFormat.xml
//convert the plist data to a Swift Dictionary
guard let plistDict = try! PropertyListSerialization.propertyList(from: plistData, options: .mutableContainersAndLeaves, format: &format) as? [String : AnyObject] else { return }
//access the values in the dictionary
if let value = plistDict["aKey"] as? String {
//do something with your value
print(value)
}
//you can also use the coalesce operator to handle possible nil values
var myValue = plistDict["aKey"] ?? ""
其他回答
我已经创建了一个简单的字典初始化器替换NSDictionary(contentsOfFile: path)。只要去掉NS。
extension Dictionary where Key == String, Value == Any {
public init?(contentsOfFile path: String) {
let url = URL(fileURLWithPath: path)
self.init(contentsOfURL: url)
}
public init?(contentsOfURL url: URL) {
guard let data = try? Data(contentsOf: url),
let dictionary = (try? PropertyListSerialization.propertyList(from: data, options: [], format: nil) as? [String: Any]) ?? nil
else { return nil }
self = dictionary
}
}
你可以这样使用它:
let filePath = Bundle.main.path(forResource: "Preferences", ofType: "plist")!
let preferences = Dictionary(contentsOfFile: filePath)!
UserDefaults.standard.register(defaults: preferences)
在SWIFT语言中，你可以这样读plist:
let path = NSBundle.mainBundle().pathForResource("PriceList", ofType: "plist")
let dict = NSDictionary(contentsOfFile: path)
读单个字典值:
let test: AnyObject = dict.objectForKey("index1")
如果你想在plist中获得完整的多维字典:
let value: AnyObject = dict.objectForKey("index2").objectForKey("date")
下面是plist:
<plist version="1.0">
<dict>
<key>index2</key>
<dict>
<key>date</key>
<string>20140610</string>
<key>amount</key>
<string>110</string>
</dict>
<key>index1</key>
<dict>
<key>amount</key>
<string>125</string>
<key>date</key>
<string>20140212</string>
</dict>
</dict>
</plist>
Plist是一个简单的Swift枚举，用于处理属性列表。
// load an applications info.plist data
let info = Plist(NSBundle.mainBundle().infoDictionary)
let identifier = info["CFBundleIndentifier"].string!
更多的例子:
import Plist
// initialize using an NSDictionary
// and retrieve keyed values
let info = Plist(dict)
let name = info["name"].string ?? ""
let age = info["age"].int ?? 0
// initialize using an NSArray
// and retrieve indexed values
let info = Plist(array)
let itemAtIndex0 = info[0].value
// utility initiaizer to load a plist file at specified path
let info = Plist(path: "path_to_plist_file")
// we support index chaining - you can get to a dictionary from an array via
// a dictionary and so on
// don't worry, the following will not fail with errors in case
// the index path is invalid
if let complicatedAccessOfSomeStringValueOfInterest = info["dictKey"][10]["anotherKey"].string {
// do something
}
else {
// data cannot be indexed
}
// you can also re-use parts of a plist data structure
let info = Plist(...)
let firstSection = info["Sections"][0]["SectionData"]
let sectionKey = firstSection["key"].string!
let sectionSecret = firstSection["secret"].int!
Plist.swift
Plist本身非常简单，下面是它的清单，以防你直接引用。
//
// Plist.swift
//
import Foundation
public enum Plist {
case dictionary(NSDictionary)
case Array(NSArray)
case Value(Any)
case none
public init(_ dict: NSDictionary) {
self = .dictionary(dict)
}
public init(_ array: NSArray) {
self = .Array(array)
}
public init(_ value: Any?) {
self = Plist.wrap(value)
}
}
// MARK:- initialize from a path
extension Plist {
public init(path: String) {
if let dict = NSDictionary(contentsOfFile: path) {
self = .dictionary(dict)
}
else if let array = NSArray(contentsOfFile: path) {
self = .Array(array)
}
else {
self = .none
}
}
}
// MARK:- private helpers
extension Plist {
/// wraps a given object to a Plist
fileprivate static func wrap(_ object: Any?) -> Plist {
if let dict = object as? NSDictionary {
return .dictionary(dict)
}
if let array = object as? NSArray {
return .Array(array)
}
if let value = object {
return .Value(value)
}
return .none
}
/// tries to cast to an optional T
fileprivate func cast<T>() -> T? {
switch self {
case let .Value(value):
return value as? T
default:
return nil
}
}
}
// MARK:- subscripting
extension Plist {
/// index a dictionary
public subscript(key: String) -> Plist {
switch self {
case let .dictionary(dict):
let v = dict.object(forKey: key)
return Plist.wrap(v)
default:
return .none
}
}
/// index an array
public subscript(index: Int) -> Plist {
switch self {
case let .Array(array):
if index >= 0 && index < array.count {
return Plist.wrap(array[index])
}
return .none
default:
return .none
}
}
}
// MARK:- Value extraction
extension Plist {
public var string: String? { return cast() }
public var int: Int? { return cast() }
public var double: Double? { return cast() }
public var float: Float? { return cast() }
public var date: Date? { return cast() }
public var data: Data? { return cast() }
public var number: NSNumber? { return cast() }
public var bool: Bool? { return cast() }
// unwraps and returns the underlying value
public var value: Any? {
switch self {
case let .Value(value):
return value
case let .dictionary(dict):
return dict
case let .Array(array):
return array
case .none:
return nil
}
}
// returns the underlying array
public var array: NSArray? {
switch self {
case let .Array(array):
return array
default:
return nil
}
}
// returns the underlying dictionary
public var dict: NSDictionary? {
switch self {
case let .dictionary(dict):
return dict
default:
return nil
}
}
}
// MARK:- CustomStringConvertible
extension Plist : CustomStringConvertible {
public var description:String {
switch self {
case let .Array(array): return "(array \(array))"
case let .dictionary(dict): return "(dict \(dict))"
case let .Value(value): return "(value \(value))"
case .none: return "(none)"
}
}
}
这个答案使用Swift本机对象而不是NSDictionary。
斯威夫特3.0
//get the path of the plist file
guard let plistPath = Bundle.main.path(forResource: "level1", ofType: "plist") else { return }
//load the plist as data in memory
guard let plistData = FileManager.default.contents(atPath: plistPath) else { return }
//use the format of a property list (xml)
var format = PropertyListSerialization.PropertyListFormat.xml
//convert the plist data to a Swift Dictionary
guard let plistDict = try! PropertyListSerialization.propertyList(from: plistData, options: .mutableContainersAndLeaves, format: &format) as? [String : AnyObject] else { return }
//access the values in the dictionary
if let value = plistDict["aKey"] as? String {
//do something with your value
print(value)
}
//you can also use the coalesce operator to handle possible nil values
var myValue = plistDict["aKey"] ?? ""
Swift -读写plist和文本文件....
override func viewDidLoad() {
super.viewDidLoad()
let fileManager = (NSFileManager .defaultManager())
let directorys : [String]? = NSSearchPathForDirectoriesInDomains(NSSearchPathDirectory.DocumentDirectory,NSSearchPathDomainMask.AllDomainsMask, true) as? [String]
if (directorys != nil){
let directories:[String] = directorys!;
let dictionary = directories[0]; //documents directory
// Create and insert the data into the Plist file ....
let plistfile = "myPlist.plist"
var myDictionary: NSMutableDictionary = ["Content": "This is a sample Plist file ........."]
let plistpath = dictionary.stringByAppendingPathComponent(plistfile);
if !fileManager .fileExistsAtPath(plistpath){//writing Plist file
myDictionary.writeToFile(plistpath, atomically: false)
}
else{ //Reading Plist file
println("Plist file found")
let resultDictionary = NSMutableDictionary(contentsOfFile: plistpath)
println(resultDictionary?.description)
}
// Create and insert the data into the Text file ....
let textfile = "myText.txt"
let sampleText = "This is a sample text file ......... "
let textpath = dictionary.stringByAppendingPathComponent(textfile);
if !fileManager .fileExistsAtPath(textpath){//writing text file
sampleText.writeToFile(textpath, atomically: false, encoding: NSUTF8StringEncoding, error: nil);
} else{
//Reading text file
let reulttext = String(contentsOfFile: textpath, encoding: NSUTF8StringEncoding, error: nil)
println(reulttext)
}
}
else {
println("directory is empty")
}
}
